1 files changed, 8 insertions, 4 deletions

diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 74db2be75dd6..8ae65c9c020c 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -2945,7 +2945,7 @@ static int ocfs2_duplicate_clusters_by_page(handle_t *handle,
 
         while (offset < end) {
                 page_index = offset >> PAGE_CACHE_SHIFT;
-                map_end = (page_index + 1) << PAGE_CACHE_SHIFT;
+                map_end = ((loff_t)page_index + 1) << PAGE_CACHE_SHIFT;
                 if (map_end > end)
                         map_end = end;
 
@@ -2957,8 +2957,12 @@ static int ocfs2_duplicate_clusters_by_page(handle_t *handle,
 
                 page = grab_cache_page(mapping, page_index);
 
-                /* This page can't be dirtied before we CoW it out. */
-                BUG_ON(PageDirty(page));
+                /*
+                 * In case PAGE_CACHE_SIZE <= CLUSTER_SIZE, This page
+                 * can't be dirtied before we CoW it out.
+                 */
+                if (PAGE_CACHE_SIZE <= OCFS2_SB(sb)->s_clustersize)
+                        BUG_ON(PageDirty(page));
 
                 if (!PageUptodate(page)) {
                         ret = block_read_full_page(page, ocfs2_get_block);
@@ -3170,7 +3174,7 @@ static int ocfs2_cow_sync_writeback(struct super_block *sb,
 
         while (offset < end) {
                 page_index = offset >> PAGE_CACHE_SHIFT;
-                map_end = (page_index + 1) << PAGE_CACHE_SHIFT;
+                map_end = ((loff_t)page_index + 1) << PAGE_CACHE_SHIFT;
                 if (map_end > end)
                         map_end = end;